A soldier walks through a destroyed classroom of a school in Gwoza, Nigeria. The city is the former base of Boko Haram and was recently retaken by the Nigerian military. (Jane Hahn for The Washington Post)

Even as Boko Haram militants wreaked havoc on northeastern Nigeria in recent months, it was sometimes difficult to discern the breadth of the destruction. Now, with a UNICEF report released Monday, we have one more indicator of the group’s indiscriminate violence.

More than 800,000 Nigerian children were forced to flee their homes in the past year and hundreds more were killed by the radical Islamist group, according to the report.

[Read: War-torn Nigerian town shows devastating legacy of Boko Haram]

“Children have also become weapons, made to fight alongside armed groups and at times used as human bombs,” the report said, “including a case of young girl sent to her death with a bomb strapped to her chest.”

As military forces have pushed Boko Haram out of its strongholds in recent months, the effects of the group's destructive campaign can be seen in a number of cities. Homes and schools have been looted and burned, bullet casings have been left scattered on the ground. Nigerian troops have found wooden guns apparently used to train Boko Haram’s child soldiers.

“Children have become deliberate targets, often subjected to extreme violence – from sexual abuse and forced marriage to kidnappings and brutal killings,” says the report, called "Missing Childhoods."

The children who survived are in many cases far from schools and health services. Makeshift camps have been erected for the displaced across the northeast, but many of the facilities have few resources.

The horrors of Boko Haram came to the world’s attention last April, when more than 200 schoolgirls were kidnapped in a village called Chibok. The attack caused global outrage, but it did not lead to the girls' rescue. Tuesday marks a year since their disappearance.

Nigerian and U.S. officials are still hopeful that the students will be found, but they’ve also acknowledged a sad reality — the girls are probably mothers by now, forced by their captors to bear children.

“According to accounts by escapees, young women and girls who have been abducted have been subjected to forced marriage, forcible religious conversion, physical and psychological abuse, forced labor and rape,” the report said.

Read more:

Dispatch: I’ve seen the Taliban’s brutality in Afghanistan. Boko Haram might be worse.

War-torn Nigerian town shows devastating legacy of Boko Haram

What captivity is like for schoolgirls kidnapped by Boko Haram